Now add this class to the project. To do this, right click on the WCF Service project and select Add existing item. Then browse to above path and select Product.cs

Host the WCF Service in IIS

To work with SPLInq in WCF service, we need to host the service in IIS with the same application pool SharePoint is running. See the below link for step by step explanation on how to host WCF 4.0 Service in IIS 7.5

Right click on Reference and select Add Reference. To locate Microsoft.SharePoint and Microsoft.SharePoint.Linq dll browse to C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\ISAPI. All the SharePoint dll are here in this location. Add the namespace

Nwind is the name of the namespace of the data context class we created in previous steps. We need to make sure that we have added Product class to the WCF Service application project as Add an Existing item. Create Service Contract We need to create Service contract. There would be four operation contracts each for one operation on Sharepoint list. IService1.cs